1. Field of the Invention
The present invention relates to a belt replacement timing annunciator, and more particularly to a belt replacement timing annunciator for informing the driver of a vehicle of the necessity of replacement of the endless belt in an automatic, belt-type transmission.
2. Description of the Background Art
Since the endless belt in a belt-type automatic transmission mounted on a vehicle of the background art is worn away by contact with a pulley during operation, the endless belt is indicated as requiring replacement when the integrated mileage of the vehicle exceeds a predetermined reference value in the service manual. A belt-type automatic transmission in which the change gear ratio of the automatic transmission is displayed on the meter panel is described in Japanese Patent Laid-Open No.53558/1989. In the stepless, variable power transmission system described in this patent publication, a potentiometer is provided for detecting the movement zone of a movable pulley for a drive pulley on which an endless belt is routed. The output of the potentiometer is converted into the change gear ratio, and the change gear ratio is displayed on the change gear ratio display provided on the meter panel.
Since the actual extent of wear of the endless belt varies depending on the vehicle operating conditions, and therefore differs significantly from the timing of belt replacement based on the integrated mileage indicated in the service manual, a system that can properly indicate the necessity of belt replacement based on the actual wear of the endless belt would be desirable in the background art.
The technology in the related art disclosed in the aforementioned patent publication is a system that simply displays the actual change gear ratio of the stepless, variable power transmission system, and the timing of replacement of the endless belt in relation to the gear ratio is not considered.
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
An object of the present invention is to improve the maintainability of a vehicle by keeping track of the wear conditions of an endless belt in a belt-type, automatic transmission system.
A further object of the present invention is to accurately and clearly inform the driver of the proper timing for replacement of the belt in the aforementioned transmission system.
These and other objects are accomplished by a belt replacement timing annunciator for an automatic transmission mounted on a vehicle provided with an endless belt routed between a drive pulley connected to an output shaft of an engine and a driven pulley connected to an axle of a driving wheel, wherein a change gear ratio is shifted by changing radii of the endless belt according to operating conditions of the vehicle, the annunciator comprising means for detecting specific operating conditions of the vehicle; means for detecting an actual change gear ratio of the automatic transmission; means for determining that the endless belt requires replacement, wherein the means for determining outputs a determination if the actual change gear ratio exceeds a predetermined reference change gear ratio for the specific operating condition; and means for displaying the result of the determination of the means for determining.
These and other objects are further accomplished by a belt replacement timing annunciator for an automatic transmission mounted on a vehicle provided with an endless belt routed between a drive pulley connected to an output shaft of an engine and a driven pulley connected to an axle of a driving wheel, wherein a change gear ratio is shifted by changing radii of the endless belt according to operating conditions of the vehicle, the annunciator comprising an electronic control unit; a pair of revolution sensors providing a number of output shaft revolutions signals and a vehicle velocity signal; a throttle valve opening sensor for recording a degree of throttle valve opening signal; a microcomputer, the microcomputer processing the signals from the sensors, recording an integrated mileage value L and calculating an actual change gear ratio and comparing the actual change gear ratio to a predetermined reference change gear ratio; an LED display for indicating a belt replacement signal when the actual change gear ratio is abnormal to the predetermined reference change gear ratio; and a resetting device for clearing a belt replacement signal based upon an operator input.
Therefore, in contrast to the related art described above, the wear condition of the endless belt reflecting various operating conditions of the vehicle, which were heretofore difficult to identify from the integrated mileage alone, can be identified adequately and properly with the present invention. Accordingly, the endless belt can be replaced at proper intervals and the maintainability of the vehicle is improved.
The present invention prevents an erroneous determination of the timing of belt replacement based on the variable change gear ratios calculated during variations in operating condition of the vehicle. Accordingly, a reliable determination of belt replacement intervals is realized.
According to the an aspect of the invention, the reference change gear ratio is determined based on the minimum predetermined change gear ratio that is determined during operating conditions in which the effect on the predetermined change gear ratio is smaller than the operating conditions at other predetermined change gear ratios, and the actual change gear ratio is detected in that reliable operating condition.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.